A fracture mechanics based model for the analysis of seal effectiveness

Abstract

The fluid containment in vessels, pipes, containers, etc. often requires the use of seals in order to assure the absence of leak in the junction zones. Sealing mechanism is typically achieved through the use of elastomeric elements that form contact with the surrounding rigid materials the containers are made of. A proper design and safety evaluation of the containment capacity of seals requires the careful evaluation of the contact pressure distribution between the soft (seal) and hard (vessel) elements. In the present paper such a problem is considered and solved through contact stress and strain evaluation based on fracture mechanics; numerical and experimental analyses on elastomeric elements are considered in order to verify the proposed modeling procedure. It is shown that the desired safety level against leakage can be ensured on the basis of the classical fracture mechanics parameters when the seal crack tip exists, or through contact strain assessment when the stress singularity vanishes. Such results can be useful in the design of seal shapes and for estimating the pressure to be applied to the sealed bodies in order to guarantee no leaks. Finally, some final relevant conclusions on the present study on leak containment are drawn.

Numerical Simulation of Static Seal Contact Mechanics Including Hydrostatic Load at the Contacting Interface

“…The bottom contacting surface is meshed with maximum element sizes equal to 2 × 10 −3 λ, 1 × 10 −3 λ and 5 × 10 −4 λ, with an element growth rate of 1.05. This resulted in meshes with 8367, 16,467 and 32,253 regular-and 682, 1210 and 2236 edge elements, respectively. Westergaard gave an analytical solution for a periodic cosinusoidal surface contact with a rigid flat surface, for linear elastic material under the half-space assumption .…”

“…In addition, the increased sealed fluid pressure can propagate the fluid front within the contact interface, as observed in both the experiment and finite element simulation [15]. This phenomenon can be explained by the linear elastic fracture mechanics (LEFM) theory [16]. So the fluid load must be considered for the cases where the fluid is present between the sealing surfaces [17,18].…”